Production of sulphuric acid



C. H. IVIADOWELI.. PRODUCTION OF SULPHURIC ACID.

APPLICATION FILED JAN. 20, 1921.

Patented Jan. 10,1922,

IAOIQMM VAWNQQQ CHARLES H.r MCDOQWELL, OF CHICAGO, ILLINOIS, ASSIGNOR TOARMOUR FERTILIZER WORKS, F CHICGO, ILLINOIS,' A CORJPOB/TION 0F NEWJERSEY.

PROD'UGTJION OJEQS'UL'IPHUMC CID.

burning of sulphur or pyrites, have been passed through a Glover-towerin the' usual way over the loose packing or filling of which tricklesdown a mixture of nitrous vitriol from the Gray-Lussac tower` and weakacid from thechambers in such proportions that they arrive at the.bottom of the tower as denitrated sulphuric acid.

The gases now pass on tothe large-volume leadchambers where they meetwith steam or with water converted into a ine spray. f' o Here thecustomary reaction takes place whereby thegchamber acid is formed, the

'gaseous mixture flowing on through the Gay-Lussac tower, such mixturecontaining the whole of the free nitrogen `of the air which had enteredinto the pyrites or sulyphur burners, together with a portion only ofthe oxygen originally present therein, suchV excess of oxygen beingrequired in order to carry out the conversion of the sulphur dioxideinto sulphuric acid as completely as possible, traces of sulphur dioxideand some oxides of nitrogen.

In such Gay-Lussac tower the sulphuric acid Hows down insnHic-ientquantity to retain the nitrous vapors, the waste gases ultimately beingdrawn olf by a chimneyr or sometimes by mechanical means.

'Many-attempts have been made to'reduce the chamber space by apparatusintended to bring about a better mixture of the gases, and to facilitatethe interaction of the misty nitrous gases and dilute acid ioatiiig inthe chamber with each other and with the chamber atmosphere. To this endreactiontowers have been placed between the chambers, but, though thisand similar apparatus have proved to be useful in the later stages ofthe process, it has not been yfound Patented Jan. ttl?, i922.

Application filed January 20, 1921. Serial No. 438,556.

practicable to do away with the lead-chambers entirely.

'Since the react-ions occur among gases and liquids in a nebulous state,vast spaces must, be provided in which the process may be carried out asquickly as possible before the waste l gases are allowed to escape intothe outer air. Such spaces have heretofore been supplied in the form Uoflarge leadchambers which are relatively expensive pieces of apparatus.

To complete they reaction and to secure the best results, lthetemperature of the gases should be reduced in the successive chambers bythe transmission of heat through their lead walls as the percentage ofsulphur dioxide decreases, although the reaction takes place in thefirst part of the system rather quickly because of the large excess ofsulphur dioxide and oxygen, the temperature, and provided, of course,that `sufficient water and nitre for the reaction is4 present.

The time factor is important and to complete the chemical change quicklyrequires the rapid extraction or dissipation of the original heat of thegases and the heat of the reaction. Accordingly, heretofore, suchlead-chambers have been made of a sufficiently large size to conductaway the heat through their metal walls.

v @ne leading aim of the present invention is the provision of means tocool the gases in such chambers 0comparatively rapidly and ecientlywhereby t0 remove the heat and to facilitate the chemical reaction, bywhich means the capacity of existing chamber plants may be materiallyincreased, thereby decreasing the cost of production.

0r, stated somewhat otherwise, the new invention makes possible theerection of a new plant at a substantially less cost as compared withthat of the present day plants of the same capacity. 1. A

ln the making of sulphuric acid the overhead expense is an importantitem because of the relatively heavy and expensive installation.

Hence it is highly desirable to be able to cut down such apparatus cost,thereby deheat from the gases of the lead-chambers and desirably alsothe provision of sufficient water at the same time for effecting thechemical transformations.

Obviously, water cannot be passed through the lead-chambers as acoolingemedium because of the evolution of considerable heat produced byits contact with the sulphuric acid, and, furthermore, the employment ofa substantial excess of Water for temperature-reducing purposes, even ifit coudd otherwise be so used, would detrinientally dilute the acidproduced.

I have discovered, however, that sulphuric acid of reduced temperaturemay be satisfactorily used for its cooling effects in suchlead-chambers, and, consequently, I draw off a portion of the warm acidfrom one or more of the chambers, add enough water to bring it down toaboute50o Baume, cool it, thus abstracting its original heat and thatgenerated by the d admixture with the water, and then introduce suchreduced cooled acid in the form of sprays into all of the chambers, andin some cases also into the inter mediate scrubbers or towers frequentlemployed between thechambers, at least 1n the preferred manner ofpracticing the process, eliminating the use of the ordinary separatewater sprays, because the needed water for the reaction is present inthe dilutedacid.

Thus the waterof such 'reduced acid is employed in the production ofmore sulphuric acid, while the acid of such diluted acid acts simply orchiefly as a cooling agent, keeping the temperature down and hencerendering ossible a hastening or'quickening of proc uction and anincreased capacity for the plant.

Ordinarily, the towers or scrubbers between the lead-chambers, by reasonof their filling or packing, act merely to mix or commingle the gasesthoroughly before they pass on into the next chamber thus facilitatingthe reaction therein.

In the present process and apparatus, however, the cold diluted acidintroduced into the towers or scrubbers is used to precipitate the acidmist that forms, and such portions of the apparatus may be consideredmerely in the nature of scrubbers. The cooling in such parts of theappliance is incidentally beneficial but is not the main purpose fortheir use.

To enable those skilled inthis art to fully understand the invention andto practice the same conveniently, efficiently, and economically, I haveillustrated in the accompanying drawing a suitable apparatus, supple- -Ymented by a complete detailed description below, which may be readilyemployed in carrying out the improved and novelprocess, and in bothviews of the drawing the same reference numerals have been employed forlike parts.'

In this drawing:

Figure 1 is a more or less diagrammatic side elevation of the apparatus;and

Figure 2 is a fragmentary plan view of the same.

Referring to the illustrations in such drawings, it will be observedthat as is usual the hot gases from the regular sulphur or pyritesburner or roaster 11 of approved type pass into the customaryGlover-tower l2 fed at the top with weak acid at 18 and with nitrousvitriol through a connection 14 with one (15) of the associatedGay-Lussac towers 15 and 16, acid drawn from the bottom of theGlover-tower being reduced in temperature in a cooler 17 and fed to thetop of the other or companion Gay-Lussac tower 16 through a suitableconnection 18.

N itre for replenishing is supplied by pottin or any other approvedmethod.

I* rom the top portion of the Glover-tower,

the gases flow into the upper part of a preliminary distribution-chamber19 from which they pass through a plurality of conduits or fines 21located at different eleva-l tions to the first, elongated,rather-narrow lead-chamber 22 of substantial. size and, caf pa'city.

The hot gasesl in the initial or manifold chamber 19 are subjectedthrough the side and top walls to sprays of cooled dilutedsulphuric-acid obtained from the bottom of the same chamber wherethewvithdrawn acid is vdiluted by water introduced at 23, the thusreduced or weakened acid being lowered in temperature by a cooler 24supplied with cooling or heat-extracting water 1n any approved manner,the cooled diluted acid being fed through pipe connections 25 to theseveral spray nozzles of the same chamber, as is illustrated.

The water of such weakened acid, when sprayed into the chamber, isconsumed in the usual way in the further production of sulphuric acid,whereas the cooled acid of such diluted liquid, actsmerely orprincipally as a constantly-traveling cooling medium traversing thechamber and the gases therein for conveying away a substantialproportion of the heat developed by the reaction, whereby the radiatingor heat-conducting capacity oii thel lead walls of the chamber are notrelied uponsolely for this purpose, their heat vdissipating functionbeing supplemented by the cooling action of the introduced acid of thesprays.

The heat thus taken upy by the circulating acid is abstracted by thecooling water of the cooler 24, which in addition absorbs the hea-toccasioned by the introduction of the diluent water added to thewithdrawn acid after its leaving the chamber.

Thus the lead walls of the chamber are relieved of the burden ofdisposing of such latter heat, which in the ordina-ry chamber ricami and27, the three main lead-chambers of the v particular appliance shownbeing separated from one another by suitable, packed, intermediatescrubbers 28 and 29 connected to the opposite ends ofthe two adjacentchambers by appropriate manifolds 31, 32, 33 and 34. In similar manner,the last chamber 27 is connected through a like lmanifold 35 andinterposed scrubber 36 to vthe first Gay- Lussac tower 15, and thebottoms of all four chambers and the three associated interveningscrubbers are connected together by suit# able types of conduits 37, 38,39, and 4l,

whereby the acid produced may ,readily flow from one to the other,lbeing drawn olf as aI commercial product at any appropriate point, as,for instance, from the first large chamber 22 at the point 42.

Chamber acid is withdrawn from chamber 22, admixed with water fed at43,! and lowered in temperature by a cooler 44, through which coolingwater flows in the customary way, such weakened acid of reducedtemperature being led through pipe connections 45 to the several spraysat the top and side walls of the same chamber and to the top of theadjacent scrubber 28.

These spraysfproduce the same effect in this chamber that thecorresponding ones did in the {irst distribution chamber, that is to saythey supply the water for the reaction and assist in cooling the chamberand its contents. Owing to the lengthened narrow shape or form of `thechamber and. the disposition or arrangement of the sprays, it is assuredthat all portionsof the gaseous mixture are subjected to the minuteparticles or globules of diluted acid.

The cooled, weakened acid is also delivered to the top of the scrubberand allowed to run down over its packing precipitating out the acidmist, whereby the gases are freed therefrom and consequently betterfitted for the continuance of the process in the next chamber lorGay-Lussac towers as the case may, be.

rllhus the gases in all the chambers are treated' in like manner for thesame purpose, each having its own cooler 44 and means 43 for theaddition of water, the diluted cooled acid being also fed to the top ofthe next scrubber.

Afan 46 for drawing the gases throughy thei apparatus is employed in thegas connection 47 between the last'scrubber 36 andl the first Gay-Lussactower- 15, an appropriate pump 48 being inserted in the connection 49between the top ofthe first Gay- Lussac tower and the bottom of thesecond like tower, from the top of which the waste gases escape througha discharge connection 51, other parts, not shown, for the circulationof the acid as described being provided where needed. l

As has been presented, it is preferable to feed the necessary water tothe chambers as an ingredient or constituent of the dilute acid, becauseit permits the ready and economical abstraction of the heat caused byits union with. the acid outside of the lead chamber, thus reducing theheat-dissipating load on the lead walls of the latter. If preferred forany reason, the water can be fedd to the chambers separately from theaci The amountof waten employed for reducing or diluting the acid isreadily ascer' tained by the Baume reading of the product, ]ust eiioughbeing used to maintain such reading at a predetermined figure, forexample, 50 degrees.

EFhe amount of cooled acid recirculatedthrough the chambers andassociated or intervening scrubbers is from about five to twenty timesthe amount of acid produced in the system and-by constantly cooling suchacid and byV developing the reactionl heat, caused by the added water,outside of the chambers where it can be easily gotten rid of, thecapacity of the plant as a whole can be largely increased over acorresponding plant not employing such cooling medium.

Inasmuch as suchv reaction water is introduced into the undivided bodyof gaseous mixture at several sides or angles in an almost infinitenumber of extremely small globules or drops, the chemical transformationproceeds with abundant eiiciency because all portions of the gas areadequately charged with such small particles of the water, thusfacilitating and aiding the chemical reaction. The cooling acid beinglikewise injected or introduced into the gaseous body is particularlywell fitted to perform its cooling function throughoutthe entire body ofgas.

In the actual commercial practice of the process, the acid product is ofapproximately 50 degrees Baume, the average'temperature in the initialdistribution chamber being about 200 to 220 degrees Fahrenheit, thecooled diluted acid of its lsprays being in the neighborhood of 1'50 to160 degrees Fahrenheit; the average temperature ini the first largelead-chamber being about 170 degrees Fahrenheit, the weakened acid ofits sprays being approximately 120 to 130 degrees Fahrenheit;l thecorresponding temperature heit, its diluted cooled acidbeing around9()r` to 100degrees Fahrenheit.

ln the manufacture of sulphuric acid on a commercial scale, the firstcost of the installation is relatively high, by reason of the size ofthe plant and the materials employed, necessitating a comparativelyheavy overhead operating-expense. Anything, therefore, which willsubstantially augment or enlarge the capacit-y of existing plants orwhich will .permit the erection of new plants of a given capacity at amaterially lessened eX- pense is of importance and the improvedsystem ofcooling constituting the subject matter of this invention meet-s t-heserequirements in that a plant fitted with this cooling arrangement willproduce a greatly increased tonnage of the product, other complementaryparts of the apparatus being operated in a coordinated manner to effectsuch increase in production, because the heretofore limiting andrestricting capability of 'the chamber lead walls to dispose of the heatby radiation and convection to the outer air is henceforth ofcomparatively little moment as their work may be supplemented by the useof the cooling acid.

A feature of advantage resides in employing separate coolers for theseveral chambers, because, as their acids are of distinctly differenttemperatures, it is more economical and etlicient, by reason of thegreater possible range of permissible temperature in the cooling waterof thecoolersassociat-ed with the earlier chambers, to employ such asegregation, but, of course, a lesser number of cooling appliances maybe used, or even one only may bel employed, if preferred, and thetemperature-reducing acid 'may be drawn from all or any one or more ofthe several chambers.

The apparatus illustrated, forms the subjectmatter of an independentpatent application, Serial No. 451116,.fled March 10, 1921, andrepresents the preferred arrangement of the parts of the appliance atthe present time, although, of course, it is susceptible of more or lessradical structural changes.

Those skilled in this art will readily appreciate that many changes maybe incorporated in the processor method herein presented Withoutdeparture from the substance and essence of the invention and withoutthe sacrifice of any of its substantial benefits and advantages. Theappended claims defining the invention include all vsuch obviousexpedients falling Within their scope. f

I claim:

l. In the chamber process of making sulphuric acid in a plurality ofchambers connected together in series, the spraying and cooling of theundivided gaseous mixture in each chamber with sulphuric acid withdrawnfrom the corresponding chamber and first diluted and then cooled beforeits employment in the spray.

2. In the chamber process of making sulphuric acid in a plurality ofchambers connected together in series, the spraying and cooling of theundivided gaseous mixture in each chamber. with sulphuric acid withdrawnfrom the corresponding chamber and first diluted and then cooled beforeits employment in the spray, and scrubbing the gases during theirpassage between chambers with such diluted cooled sulphuric acid.

3. In the chamber process of making sulphuric acid in aplurality ofchambers connected together in series, the spraying and cooling of theundivided gaseous mixture in each chamber with sulphuric acid withdrawnfrom the corresponding chamber and first diluted and then cooled beforeits employment in the spray, and scrubbing the gases during theirpassage between chambers by diluted cooled sulphuric acid withdrawn fromthe next adjacent chamber.

' CHARLES H. MACDOVVELL.

